As mentioned in the footnote, I was referring to the individuals hacked, not the parties. In addition to the political parties, the hack also targeted youtubers, artists, musicians, etc.
These include Christian Ehring, Jan Böhmermann, Oliver Welke (all hosts of left-leaning late night or satire shows), Marteria, Casper, K.I.Z. (left-leaning rappers/music groups, or in case of K.I.Z. even explicitly anti-capitalist), and several YouTubers.
Additionally, the twitter account doing the hacks has mocked Böhmermann's Reconquista Internet explicitly.
The problem is that any side was targeted.
I guess the thinking is "it's targeted against one side, so probably look at the other to find the perp". Would be just as true with hacked right-wingers.
(and the corollary: "it's a flag-flag operation by the very same side, so look there", which also comes up no matter what side is affected)
1) not true, FDP and CDU are certainly not left-wing
2) even if it were true, would it be more ethical to hack right-wingers?
The current speculation indicates no political leaning whatsoever (apart from one password of one leak for one socialist politician was "linkenshit" which could be either neutral, positive or negative).
Considering the age of the leaked data, it is speculated that during the time of gathering data, the AfD was not part of the targeted parliaments.